In order to make "freeze" attacks against the update logic harder let's
add the ability to encode a "Best Before" date into SHA256SUMS directory
listings: if the current time is already beyond that time, we'll ignore
the SHA256SUMS as "stale" and fail the upgrade. Or in other words: the
freeze attack will now result in a client-side error eventually, instead
of success state.
The best before data is encoded in an optional pseudo-file listed in SHA256SUMS:
any file named BEST-BEFORE-YYYY-MM-DD.
Since c5de7b14ae
file searching implies a new mount api syscall by default,
to trigger automounts.
But, this is not necessary in most cases, e.g. when chasing
syspath in sd-device (actually this causes regression in umockdev,
see https://github.com/martinpitt/umockdev/issues/271).
Another example is reading unit files, especially .network files,
as automount may trigger mounting network filesystems...
Also, when this is used in NSS plugins, programs that load the
plugins may fail because of spuriously configured seccomp. See #38565.
Let's not trigger automount by default, and do only when explicitly
requested.
This introduces CHASE_TRIGGER_AUTOFS, and use it in
- service manager,
- bootctl and finding ESP/xbootldr,
- sysupdate,
- mountfsd,
- systemd-mount.
There may be several more places we should trigger automount, but let's
do that later.
Follow-up for c5de7b14ae.
Fixes#38565.
Replaces #38569.
Co-authored-by: Luca Boccassi <luca.boccassi@gmail.com>
This reverts commit 490aa05ca1.
As commented https://github.com/systemd/systemd/pull/38569#discussion_r2284978273,
the commit makes autofs check bypassed. Before the commit, when
CHASE_NO_AUTOFS is set, we did not shortcut chasing paths, and refused
any autofs mount points in the path. However, with the commit, the flag
was swapped but even when CHASE_AUTOFS is unset, the autofs check may be
skipped.
To fix the issue, rather than swapping the flag, we should introduce
another flag, say CHASE_TRIGGER_AUTOFS. This revert the commit, and in a
later commit, the new flag will be introduced.
Since https://github.com/systemd/systemd/commit/c5de7b14ae2e08d267d8d75bc88934ac6aa7dcd6
file searching implies a new mount api syscall by default,
to trigger automounts.
This is problematic in NSS plugins, as they are dlopen'ed inside
processes by glibc, for two reasons.
First of all, potentially searching on a networked filesystem
automount could lead to nasty surprises, such as the process
responsible for setting up the network filesystem trying to
search on that same filesystem.
More importantly, the new mount api syscall was never part of
the filesystem seccomp filter that we provide by default, and
given mounting/remounting/bind mounting is one of the possible
ways to bypass sandboxing it is very likely not allowed when
custom filters are used in sandboxed processes, if they don't
need to do these operations otherwise.
The filesystem seccomp mask we provide has been updated, however
this only takes effect on the next restart of a service. When
systemd is upgraded via a package upgrade, the new nss plugin is
installed and will be immediately dlopen'ed by glibc when needed,
without waiting for the process to restart, which means the existing
seccomp filter applies, causing the filter to trigger.
Given it's not really possible for any arbitrary program to
predict which NSS modules glibc will load, given programs do not
configure that and instead nsswitch is set up by the sysadmin,
it's impossible to handle at each process level. It's also not
possible to know when it will be triggered, given the plugin
is not linked in each binary tools like need-restart cannot
even pre-emptively restart services that may be affected.
This means in practice, upgrading from systemd << v258 to >= v258
requires a reboot to avoid either subtle or catastrophic system
failures.
By avoiding to trigger automounts in nss-systemd we can avoid
both issues.
userdb drop-ins are searched for in:
/etc/userdb/
/run/userdb/
/run/host/userdb/
/usr/local/lib/userdb/
/usr/lib/userdb/
none of which are supported as automounts anyway.
Note that this happens only when the userdbd service is not running,
as otherwise nss-systemd will go through the varlink IPC, rather than
doing the searches in-process.
So invert CHASE_NO_AUTOFS to CHASE_AUTOFS and set it in the places where
we do want to trigger automounts, like looking for the ESP.
Follow-up for https://github.com/systemd/systemd/commit/c5de7b14ae2e08d267d8d75bc88934ac6aa7dcd6
Fixes https://github.com/systemd/systemd/issues/38565
Admittedly, some of our glyphs _are_ special, e.g. "O=" for SPECIAL_GLYPH_TOUCH ;)
But we don't need this in the name. The very long names make some invocations
very wordy, e.g. special_glyph(SPECIAL_GLYPH_SLIGHTLY_UNHAPPY_SMILEY).
Also, I want to add GLYPH_SPACE, which is not special at all.
In mkosi, I want to add a sysupdate verb to wrap systemd-sysupdate.
The definitions will be picked up from mkosi.sysupdate/ and passed
to systemd-sysupdate. I want users to be able to write transfer
definitions that are independent of the output directory used by
mkosi. To make this possible, it should be possible to specify the
directory that transfer sources should be looked up in on the sysupdate
command line. Let's allow this via a new --transfer-source= option.
Additionally, transfer sources that want to take advantage of this
feature should specify PathRelativeTo=directory to indicate the configured
Path= is interpreted relative to the tranfer source directory specified
on the CLI.
This allows for the following transfer definition to be put in
mkosi.sysupdate:
"""
[Transfer]
ProtectVersion=%A
[Source]
Type=regular-file
Path=/
PathRelativeTo=directory
MatchPattern=ParticleOS_@v.usr-%a.@u.raw
[Target]
Type=partition
Path=auto
MatchPattern=ParticleOS_@v
MatchPartitionType=usr
PartitionFlags=0
ReadOnly=1
"""
The current implementation will never find a match, because in the event
of a match instance_cmp falls through to comparing paths and the key
we're matching against will always have a path of NULL.
So let's just use a separate compare function, just to make sure future
updates to instance_cmp don't break resource_find_instance again.
Sometimes it makes sense to hard kill a client if we die. Let's hence
add a third FORK_DEATHSIG flag for this purpose: FORK_DEATHSIG_SIGKILL.
To make things less confusing this also renames FORK_DEATHSIG to
FORK_DEATHSIG_SIGTERM to make clear it sends SIGTERM. We already had
FORK_DEATHSIG_SIGINT, hence this makes things nicely symmetric.
A bunch of users are switched over for FORK_DEATHSIG_SIGKILL where we
know it's safe to abort things abruptly. This should make some kernel
cases more robust, since we cannot get confused by signal masks or such.
While we are at it, also fix a bunch of bugs where we didn't take
FORK_DEATHSIG_SIGINT into account in safe_fork()
We use it for more than just pipe() arrays. For example also for
socketpair(). Hence let's give it a generic name.
Also add EBADF_TRIPLET to mirror this for things like
stdin/stdout/stderr arrays, which we use a bunch of times.
`MatchPattern` for regular-file and directory as target can now match
subdirectories This is useful to install files for examples in `.extra.d`
directories:
```
[Target]
Type=regular-file
Path=/EFI/Linux
PathRelativeTo=boot
MatchPattern=gnomeos_@v.efi.extra.d/apparmor.addon.efi
```
The if the directories in the path do not exist, they will be created. Whereas
the part in `Path` is not created.
As described in the BLS, we should place binaries into the XBOOTLDR
directory if it is available, otherwise into the ESP. Thus, we might
need to put binaries into /boot or into /efi depending on the existence
of the XBOOTLDR partition.
With this change, we introduce a new PathRelativeTo= config option that
makes this functionality possible
Chasing symlinks is a core function that's used in a lot of places
so it deservers a less verbose names so let's rename it to chase()
and chaseat().
We also slightly change the pattern used for the chaseat() helpers
so we get chase_and_openat() and similar.
-1 was used everywhere, but -EBADF or -EBADFD started being used in various
places. Let's make things consistent in the new style.
Note that there are two candidates:
EBADF 9 Bad file descriptor
EBADFD 77 File descriptor in bad state
Since we're initializating the fd, we're just assigning a value that means
"no fd yet", so it's just a bad file descriptor, and the first errno fits
better. If instead we had a valid file descriptor that became invalid because
of some operation or state change, the other errno would fit better.
In some places, initialization is dropped if unnecessary.
The existing logic can't find the root device in scenarios where
the root has been replaced with an overlay. We support looking
at "/run/systemd/volatile-root" to find the original root, similar
to what systemd-repart and gpt-auto-generator do.
Instead of exposing just the partition type UUID, let's expose the
GptPartitionType struct, which has a lot more information available
in a much more accessible way.
Also, let's get rid of SECONDARY/OTHER in PartitionDesignator. These
were only there to support preferred architectures in dissect-image.c,
but we can easily handle that by comparing architectures when we decide
whether to override a partition. This is done in a new function
compare_arch().
In sd-device, `devpath` is a kind of syspath without '/sys' prefix, e.g.
/devices/pci0000:00/0000:00:1c.4/0000:3c:00.0/nvme/nvme0/nvme0n1,
and `devname` is a path to the device node, e.g. /dev/nvme0n1.
Let's use the consistent name for the helper function.
No actual code changes, just splitting out of some dev_t handling
related calls from stat-util.[ch], they are quite a number already, and
deserve their own module now I think.
Also, try to settle on the name "devnum" as the name for the concept,
instead of "devno" or "dev" or "devid". "devnum" is the name exported in
udev APIs, hence probably best to stick to that. (this just renames a
few symbols to "devum", local variables are left untouched, to make the
patch not too invasive)
No actual code changes.
Lennart Poettering
Daan De Meyer
Yu Watanabe
Nick Labich
Zbigniew Jędrzejewski-Szmek
Adrian Vovk
Mike Yuan
Valentin David
Frantisek Sumsal
reuben olinsky
David Tardon